Monitoring System for Monitoring Surroundings of Vehicle

1. A monitoring system for monitoring surroundings of a vehicle by displaying images taken by a plurality of cameras provided at the vehicle on a display apparatus provided in a vehicle compartment, comprising: an image processing portion including: a boundary-determining means for determining a boundary of the neighboring images taken by the plurality of cameras for synthesizing the neighboring images in a horizontal direction by approximating the boundary to an exponential curve; a horizontally normalizing means for normalizing the neighboring images in a horizontal direction so that the boundary approximated to the exponential curve is converted into a linear vertical boundary; a vertically compensating means for compensating a vertical displacement between the neighboring images on the linear vertical boundary; and a pixel-adjusting means for adjusting the number of pixels of the synthesized image to the number of pixels suitable for displaying the synthesized image produced by the image processing portion on the display apparatus.

2. The monitoring system for monitoring the surroundings of the vehicle according to claim 1 , wherein each image taken by the cameras includes a horizontal reference line at a predetermined vertical level of the image, and the boundary-determining means approximates the boundary of upper side defined by an inflection point which is a crossing point of the horizontal reference line and the boundary using a function and the boundary of lower side defined by the inflection point using a different function.

3. The monitoring system for monitoring the surroundings of the vehicle according to claim 1 , wherein the horizontally normalizing means at least executes one of expansion and compression of the pixels so that the number of pixels of the images in all horizontal directions becomes equal after normalization.

4. The monitoring system for monitoring the surroundings of the vehicle according to claim 2 , wherein normalized images are combined on the vertical line vertically passing through the horizontal reference line by matching the crossing points of the horizontal reference line and the boundary of the neighboring images and a displacement of the images in a vertical direction is adjusted with a partial change of vertical scale of at least one of the neighboring images when the normalized images are combined.

5. The monitoring system for monitoring the surroundings of the vehicle according to claim 1 , wherein the image processing means further comprises a perception correcting means for correcting a perception of a user of the system by changing a far horizontal line linearly imaged in each image taken by the plurality of cameras to one consecutive circularly curved line in the synthesized image and by changing a near horizontal line linearly imaged in each image taken by the cameras to another consecutive circularly curved line, curvature of which is greater than that of the one consecutive circularly curved line.

6. A monitoring system for monitoring surroundings of a vehicle by displaying images of the surroundings of the vehicle taken by a first camera and a second camera provided at the vehicle on a display apparatus provided in a vehicle compartment, comprising: an image processing portion including: a boundary-determining means for determining a boundary of neighboring first image taken by the first camera and second image taken by the second camera for synthesizing the neighboring first image and the second image in a horizontal direction by approximating the boundary to an exponential curve; a horizontally normalizing means for normalizing the neighboring first image and second image in a horizontal direction so as to be converted the boundary approximated to the exponential curve into a linear vertical boundary; a vertically compensating means for compensating a vertical displacement between the neighboring first image and second image on the linear vertical boundary; and a pixel-adjusting means for adjusting the number of pixels of the synthesized image to the number of pixels suitable for displaying the synthesized image produced by the image processing portion on the display apparatus.

7. The monitor system for monitoring the surroundings of the vehicle according to claim 6 , wherein the first camera and the second camera are installed with a certain depression angle from the horizontal position and to have an overlapped view angle area of the first camera and the second camera.

8. The monitoring system for monitoring the surroundings of the vehicle according to claim 6 , wherein the normalization of the horizontal normalization means includes at least one of extension of the pixel to increase the number thereof by creating new pixels and compression of the pixel to decrease the number thereof by removing extra pixels.

9. The monitoring system for monitoring the surroundings of the vehicle according to claim 6 , wherein a horizontal reference line is set in each first image and second image at a predetermined position in a vertical direction.

10. The monitoring system for monitoring the surroundings of the vehicle according to claim 9 , wherein the exponential curve has an inflection point at an intersection with the horizontal reference line.

11. The monitoring system for monitoring the surroundings of the vehicle according to claim 8 , wherein the exponential function is obtained by calculating a degree of matching between overlapping portion of the neighboring images taken by the first camera and the second camera.

12. The monitoring system for monitoring the surroundings of the vehicle according to claim 9 , wherein an upper boundary point and a lower boundary point are calculated on the basis of a calculation of a degree of matching between the neighboring images, the exponential function is calculated on the basis of the horizontal reference line, the upper boundary point, and the lower boundary point, and the horizontally normalizing means conducts normalization on the basis of the exponential function.